The present invention relates to an article of furniture and, more specifically, pertains to a new and improved construction of an adjustable chair or seating structure.
In general, the present invention concerns a chair with rearwardly inclinable seat and back rest carriers. The rearwardly inclinable seat carrier is arranged to pivot at its knee side or front portion about a seat support means or swivelling component or chair base by means of a knee or front pivot joint having a horizontal axis. At its end on the back rear side or rear end, the rearwardly inclinable seat carrier is pivotably connected with the back rest carrier by means of a back rest or rear pivot joint having a horizontal axis. The back rest carrier is linked about a substantially horizontal pivot axis to the seat support means or swivelling component or chair base in a spaced relationship to the knee or front pivot joint of the seat carrier. When the seat carrier inclines rearwardly, the back rest carrier inclines at a greater angle than the inclination angle of the seat carrier. A back rest, guided on the back rest carrier, is displaced downwardly by a distance determined by the inclination of the seat carrier.
Generally speaking, the present invention also comprises a chair frame associated with a chair of the abovementioned type.
Prior art chairs with rearwardly inclinable seat carriers and back rest carriers are known in various executions. In a simple known construction, the seat carrier and the back rest carrier are each pivotably linked at one end to a carrying or swivelling component to pivot about substantially horizontal pivot axes disposed in mutually spaced relationship. The seat portion is connected at its other end through a pivot joint with the back rest carrier. During a rearward inclination of the seat portion, the back rest carrier inclines at a greater angle than the seat portion or seat carrier. For this purpose, either an additional connecting strut is associated with one of the pivot joints or one of the pivot joints is designed as a sliding joint. The greater inclination of the back rest carrier brings about the well-known undressing effect, i.e. the clothing of the chair user is pulled upwards during the rearward inclination of the chair.
To prevent the undressing effect, it is known (cf. PCT published patent application No. WO 83/00610) to arrange a back rest to the back rest carrier which is displaceable in height and which, upon rearward inclination of the seat carrier, is moved downwards a distance corresponding to the inclination of the seat carrier, so that no undressing effect occurs.
The automatically occurring displacement of the back rest in dependence of the rearward inclination of the seat carrier is achieved by means of a linkage which is linked or hingedly connected to the pivot joint of the back rest carrier at the carrying or swivelling component side thereof. This linkage requires a comparatively large amount of space, and since it is situated under the seat surface and extends up to the end of the chair at the knee side, is not only space-consuming but also expensive.